GIS Dictionary

[programming] A UML term that describes how two classes have a relationship with one or more other classes. In an N-ary association, instances of the classes in question usually exist … Read more

Acronym for North American Datum of 1927. The primary local horizontal geodetic datum and geographic coordinate system used to map the United States during the middle part of the twentieth … Read more

Acronym for North American Datum of 1983. A geocentric datum and graphic coordinate system based on the Geodetic Reference System 1980 ellipsoid (GRS80). Mainly used in North America, its measurements … Read more

1 [aerial photography] In aerial photography, the point on the ground vertically beneath the perspective center of the camera lens. 2 [astronomy] In astronomy, the point on the celestial sphere … Read more

[data structures] Acronym for North American Industry Classification System. A system for classifying individual business locations by their types of economic activity. The statistics agencies of Canada, Mexico, and the … Read more

[mathematics] Acronym for not a number.

[coordinate systems] The datum established in 1929 by the U.S. Coast and Geodetic Survey as the surface against which elevation data in the United States is referenced.

[cartography] A method of manual data classification that seeks to partition data into classes based on natural groups in the data distribution. Natural breaks occur in the histogram at the … Read more

An interpolation method for multivariate data in a Delaunay triangulation. The value for an interpolation point is estimated using weighted values of the closest surrounding points in the triangulation. These … Read more

[ESRI software] To interactively change the observer’s or target’s position using a tool designed for this purpose, such as the navigate or fly tool. There are three contexts in which … Read more

1 [wayfinding] The combined mental and physical activities involved in traveling to a destination, often a distant or unfamiliar one. Navigation comprises wayfinding and locomotion. 2 [geography] The activity of … Read more

[GPS] The name of the U.S. Department of Defense’s Global Positioning System (GPS).

A technique for resampling raster data in which the value of each cell in an output raster is calculated using the value of the nearest cell in an input raster. … Read more

[cartography] The border delineating and defining the extent of geographic data on a map. It demarcates map units so that, depending on the map projection, the neatline does not always … Read more

[mathematics] Methods of defining new values for locations using the values of other locations within a given distance or direction.

[programming] An open-source development environment that supports all Java application types.

1 [network analysis] An interconnected set of points and lines that represent possible routes from one location to another. For geometric networks, this consists of edge features, junction features, and … Read more

[network analysis] Any method of solving network problems such as traversability, rate of flow, or capacity, using network connectivity.

[ESRI software] In ArcGIS Network Analyst, a feature class or table containing network analysis objects that is stored within a network analysis layer. Network Analyst solvers read input from, and … Read more

[ESRI software] A composite layer that contains the properties and network analysis classes used in the analysis of a network problem, and the results of the analysis.

[ESRI software] In ArcGIS Network Analyst, a feature or row in a network analysis class. Network analysis objects are used as input and written as output during network analysis. A … Read more

[ESRI software] An auxiliary or additional function performed by a junction feature within a geometric network. Junction features can act as sources or sinks for calculating flow direction. If a … Read more

[ESRI software] A type of attribute associated with a network element in a network dataset. Network attributes are used to help control flow through a network (similar to a weight … Read more

[ESRI software] A collection of topologically connected network elements (edges, junctions, and turns) that are derived from network sources, typically used to represent a linear network, such as a road … Read more

[ESRI software] A component in a network dataset: an edge, junction, or turn. All elements in a network dataset share the same set of network attributes. Network elements are used … Read more

[ESRI software] A component in a geometric network: an edge or a junction. Features in a geometric network are used to model topological relationships, typically in directed flow networks such … Read more

[ESRI software] A layer that references a network dataset. In a geodatabase, a network dataset is a collection of network elements (edges, junctions and turns) that are derived from network … Read more

1 [network analysis] A geographic position in a network system. 2 [ESRI software] In ArcGIS Network Analyst, a type of network analysis object that is zero-dimensional and has a defined … Read more

[ESRI software] A connecting point in a geometric network, such as an intersection or interchange of a road network, confluence of streams in a hydrologic network, or switch in a … Read more

[Internet] A number that is used to specify direct communication over a network to an Internet application.

[ESRI software] Feature classes in a geodatabase that are used to generate and define a network dataset.

[network analysis] A function that performs network analysis on a geometric network. Specific kinds of network tracing include finding features that are connected, finding common ancestors, finding loops, tracing upstream, … Read more

[computing] A computer architecture modeled after the human brain and designed to solve problems that human brains solve well, such as recognizing patterns and making predictions from past performance. Neural … Read more

Acronym for National Marine and Electronics Association. A nonprofit association composed of manufacturers, distributors, dealers, educational institutions, and others interested in peripheral marine electronics occupations. The NMEA has created a … Read more

[data capture] In raster data, the absence of a recorded value. NoData does not equate to a zero value. While the measure of a particular attribute in a cell may … Read more

1 [ESRI software] In a geodatabase, the point representing the beginning or ending point of an edge, topologically linked to all the edges that meet there. 2 [ESRI software] In … Read more

1 [remote sensing] In remote sensing, any disturbance in a frequency band. 2 [data quality] Any irregular, sporadic, or random oscillation in a transmission signal. 3 [telecommunications] Random or repetitive … Read more

[data structures] Data divided into classes within which all elements are assumed to be equal to each other, and in which no class comes before another in sequence or importance; … Read more

[data editing] A polygon that violates topological integrity by crossing its own boundary (usually by making a small loop).

[data management] Data without inherently spatial qualities, such as attributes.

[statistics] A theoretical frequency distribution of a dataset in which the distribution of values can be graphically represented as a symmetrical bell curve. Normal distributions are typically characterized by a … Read more

[database structures] A set of guidelines for designing table and data structures in a relational database. When followed, normal form guidelines prevent data redundancy, increase database efficiency, and reduce consistency … Read more

[ESRI software] The template that is automatically loaded in ArcMap and contains all the standard toolbar and command default settings. User interface customization that is saved in the Normal template … Read more

[data management] The process of organizing, analyzing, and cleaning data to increase efficiency for data use and sharing. Normalization usually includes data structuring and refinement, redundancy and error elimination, and … Read more

[symbology] A map symbol that shows the direction of north on the map, thereby showing how the map is oriented.

1 [coordinate systems] The distance north of the origin that a point in a Cartesian coordinate system lies, measured in that system’s units. 2 [coordinate systems] The positive y-value in … Read more

[navigation] Acronym for Notice to Airmen. An advisory bulletin containing information about the National Airspace System, typically time-sensitive information between publishing cycles, or corrections to published documents and charts.

[Internet] In ArcGIS Online, status message about your group membership request.

Acronym for National Spatial Data Infrastructure. A federally mandated framework of spatial data that refers to U.S. locations, as well as the means of distributing and using that data effectively. … Read more

[data sharing] A community of digital spatial data providers that maintain NSDI Clearinghouse Nodes as part of the U.S. National Spatial Data Infrastructure.

An Internet server that hosts a collection of metadata and data maintained and stored on a computer server by a data provider. An NSDI Clearinghouse Node provides information about geographic … Read more

[navigation] Acronym for Notice to Mariners. A periodical update to existing nautical charts, issued by maritime authorities.

[spatial statistics use for geostatistics] A parameter of a covariance or semivariogram model that represents independent error, measurement error, or microscale variation at spatial scales that are too fine to … Read more

[ESRI software] A DBMS-defined restriction specifying that a column cannot contain a null value.

[statistics] A statement that essentially outlines an expected outcome when there is no pattern, no relationship, and/or no systematic cause or process at work; any observed differences are the result … Read more

[spatial statistics use for geostatistics] The absence of a recorded value for a field. A null value differs from a value of zero in that zero may represent the measure … Read more